"North Korea fired a ballistic missile into the East Sea from a site in the vicinity of Sinpo, South Hamgyong Province, at around 6:42 a.m.," the Joint Chiefs of Staff (JCS) said in a statement. "The flight distance is about 60 kilometers."
The projectile is estimated to be "a type of KN-15 medium-range ballistic missile," also known as Pukguksong-2, and the maximum altitude of its flight was 189 km, a senior JCS official later told reporters.
"It's still premature to conclude whether the test-firing was a success or failure," he added. "It was detected by South Korean Navy's Aegis ship operating in the East Sea and the Air Force's ballistic missile warning system."
He said the North seems to have aimed to test the technology of its ballistic missile technology and also considered the timing just before the U.S.-China summit.
Citing an initial assessment, the U.S. Pacific Command also said the projectile seems to be a KN-15 ballistic missile fired from a land-based facility.
It flew nine minutes, added the Hawaii-based command.
The South's presidential office convened an emergency National Security Council (NSC) meeting to discuss the provocation, presided over by Kim Kwan-jin, the national security adviser to Acting President Hwang Kyo-han.
Hwang ordered the nation's troops to strengthen their combat readiness in case of a contingency.
The North's move came as Trump plans to host the Chinese president in his Florida estate on Thursday and Friday (local time) for their first summit. The North Korea issue will likely be among top agenda items.
In an interview with the Financial Times, Trump warned that the U.S will take unilateral action to get rid of the North's military threats unless China does its part.
Two weeks ago, the North test-fired a missile, which ended in failure. Earlier in March, the North fired four ballistic missiles, three of which fell into the sea near Japan.
In February, it blasted a Pukguksong-2 intermediate-range ballistic missile (IRBM) from a mobile launcher. It flew more than 500km.
The Kim Jong-un regime conducted two nuclear tests and fired two dozen missiles last year.
Concern has grown that it may carry out another nuclear test or long-range rocket launch.
North Korea's state-controlled media remained silent about the latest missile launch. (Yonhap)